Triple Formula One world champion Sebastian Vettel has agreed a new contract extension with Red Bull through to the end of 2015.

Vettel has been a part of the team since 2009, claiming 29 victories, 39 pole positions, and winning three successive titles since 2010.

Just over two years ago, in March 2011, Vettel agreed a new three-year deal up to and including 2014, with the latest extension adding one more year.

The latest move from Red Bull represents a statement of intent, and a further warning to Ferrari that the 25-year-old is not available under any circumstances.

Vettel has long been linked with Ferrari, and as recently as last summer the strong suggestion was the German had an agreement to join the Maranello marque from next year.

Later in the year president Luca Di Montezemolo suggested managing Fernando Alonso and Vettel in the same team would be akin to having "two roosters in a henhouse".

In February, Di Montezemolo again suggested that as long as Alonso was with Ferrari, he could not envisage bringing in Vettel.

But with Vettel on course for a fourth successive title - his third win of the season in Canada on Sunday saw him open a 36-point cushion over Alonso at the head of the drivers' standings - the team have moved to tie him down.

Question marks now remain as to who will be Vettel's team-mate, with Mark Webber already 63 points down, and with only two podiums to his name this season.

Webber should have triumphed in the second race of the season in Malaysia, only for Vettel to ignore team orders to hold station behind the Australian and go on to take the chequered flag.

That episode deteriorated an already fragile relationship and paved the way for suggestions that this would be Webber's final year at Red Bull.

Team principal Christian Horner has stated over the past few months that if Webber is to be retained, he would only sit down with him to discuss a new contract later this summer.

In the meantime, Toro Rosso's Jean-Eric Vergne is starting to show signs of improvement, finishing eighth and a career-high sixth in the last two races in Monaco and Canada.